1. Technical Field
The present invention relates to a liquid ejecting head such as an ink jet recording head and a liquid ejecting apparatus. In particular, the invention relates to a liquid ejecting head that ejects liquid containing flat plate-like particles such as glitter pigment and a liquid ejecting apparatus.
2. Related Art
A liquid ejecting apparatus is an apparatus that includes a liquid ejecting head capable of ejecting liquid as ink droplets through nozzles and ejects various types of liquids from the liquid ejecting head. As a representative liquid ejecting apparatus, there is an image recording apparatus such as an ink jet recording apparatus (printer), for example. The ink jet recording apparatus includes an ink jet recording head (hereinafter, referred to as recording head) and ejects liquid-state ink as ink droplets through nozzles of the recording head so as to perform recording. In addition to this, the liquid ejecting apparatuses are used for ejection of various types of liquids such as a coloring material to be used for a color filter of a liquid crystal display or the like, an organic material to be used for an organic electroluminescence (EL) display, and an electrode material to be used for forming an electrode. A recording head for an image recording apparatus ejects liquid-state ink and a coloring material ejecting head for a display manufacturing apparatus ejects solutions of respective coloring materials of red (R), green (G), and blue (B). Further, an electrode ejecting head for an electrode forming apparatus ejects a liquid-state electrode material and a bioorganic matter ejecting head for a chip manufacturing apparatus ejects a solution of bioorganic matter.
In the liquid ejecting head employing an ink jet technique, there are provided a plurality of nozzles, pressure chambers formed for the respective nozzles, a common liquid chamber (also referred to as reservoir or manifold) common to the plurality of pressure chambers, and a liquid flow path constituted by supply paths that make the common liquid chamber and the respective pressure chambers communicate with each other, and the like. The liquid ejecting head is configured as follows. Pressure generation units such as piezoelectric elements or heat generation elements are driven to generate pressure fluctuation on liquid in the pressure chambers so that the liquid is ejected through the nozzles by using the pressure fluctuation.
In recent years, as an application example of the ink jet technique, an application in which metallic ink containing metal particles (one type of glitter pigment) as pigment is ejected is exemplified (for example, JP-A-2008-174712). In order to obtain metallic glossiness on a printed matter using the metallic ink, it is desired that the surfaces of the metal particles are as flat as possible. Therefore, the glitter pigment contained in the metallic ink is formed with flat plate-like (scale-like) particles.
Recently, recording heads have made a large progress in providing higher resolution and a nozzle formation pitch tends to be narrower. Along with this, the widths of the flow paths in the pressure chambers and the like become narrower. As the widths of the flow paths in the pressure chambers and the like are narrower, influence by viscous resistance on flow of ink in the vicinity of the flow path inner walls is larger. That is to say, turbulence flow (eddy flow) is generated on the ink in the pressure chambers due to boundary layer separation or the like. When the metallic ink is used, the flat plate-like particles revolve in a local region due to the eddy flow. If the flat plate-like particles revolve in a narrow range in the pressure chambers, there arises a problem that ink ejection is unstable. To be more specific, the flying direction of ink that is ejected through the nozzles is bent, an amount of ink that is ejected varies, and mist is easy to be generated. In the worst case, there arises a problem of a so-called missing dot that ink is not ejected.
The above-mentioned problems arise not only on the ink jet recording head that ejects the metallic ink but also other liquid ejecting heads that eject liquids containing flat plate-like particles.